Gear unit having a housing

ABSTRACT

A gear unit includes a housing, a trough for guiding oil and reducing losses due to splashing surrounding a circumferential section of a toothing part, the trough including at least three parts, e.g., at least one bottom plate and two side walls, the bottom plate being screw-connected to the two side walls, the trough being fastened to the housing, the trough having an opening, the bottom plate and the side walls being stamped bent parts.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent application Ser. No. 15/035,003, which is the national stage of PCT/EP2014/002830, having an international filing date of Oct. 21, 2014 and claiming priority to Application No. 10 2013 018 710.9, filed in the Federal Republic of Germany on Nov. 8, 2013, each of which is expressly incorporated herein in its entirety by reference thereto.

FIELD OF THE INVENTION

The present invention relates to a gear unit having a housing.

BACKGROUND INFORMATION

It is generally known that a housing of a gear unit has bearing mountings in which the bearings for the shafts of the gear unit are able to be accommodated, and the related forces are dissipated.

SUMMARY

Example embodiments of the present invention provide a gear unit having a housing, which may protect the environment and save resources.

Among features of example embodiments of the present invention with regard to the gear unit having a housing are that the housing has a housing top part and a housing bottom part, in particular, the housing top part being formed in shell-like fashion, especially like half a nutshell, the housing top part having a top wall that at least partially delimits the interior of the gear unit and is curved, especially concave, such that in the longitudinal direction and such that in the transverse direction oil droplets sprayed up toward the top wall drip off in or counter to the transverse direction along the top wall into a groove formed on the inner side of the housing top part, in particular, the amount of the gradient of the top wall, e.g., especially the slope of the top wall relative to the horizontal direction, increasing faster in the transverse direction with increasing distance from the highest point of the top wall, especially from the point of the top wall with vanishing gradient, than in the longitudinal direction.

An advantage in this case is that the top wall is inclined such that oil droplets sprayed by a toothing part, such as a gear wheel, up toward the top wall are drained off to a groove in the housing top part, and from there, are able to be supplied to parts to be lubricated with lubricating oil.

Among features of the present invention with regard to the gear unit having a housing are that the housing has a housing top part and a housing bottom part, in particular, the housing top part being formed in shell-like fashion, especially like half a nutshell, the housing top part having a top wall that at least partially delimits the interior of the gear unit and is curved, especially concave, in the longitudinal direction and in the transverse direction, the housing top part having a groove formed on its inner side, especially a groove formed integrally, e.g., in one piece on the housing top part, the amount of the gradient of the top wall, e.g., especially the slope of the top wall relative to the horizontal direction, increasing faster in the transverse direction with increasing distance from the highest surface point of the top wall, e.g., especially from the surface point of the top wall with vanishing gradient, than in the longitudinal direction.

An advantage in this case is that the top wall is inclined such that oil droplets sprayed by a toothing part, such as a gear wheel, up toward the top wall are drained off to a groove in the housing top part, and from there, are able to be supplied to parts to be lubricated with lubricating oil. The oil droplets may be conveyed along the top wall in or counter to the transverse direction, so that the grooves disposed in and/or counter to the transverse direction are supplied with oil.

The transverse direction may be aligned parallel to the axis of the output shaft, the longitudinal direction being oriented perpendicular to and/or transverse to the transverse direction, in particular, the longitudinal direction being aligned parallel to the plane defined by an axis of an intermediate shaft and an axis of an output shaft.

The top wall may be formed in a manner corresponding to a vault. An advantage in this instance is that the sprayed-up oil droplets are drained off along the vault, in order then to be conducted down along the side into a groove formed on the inner side.

Lubricating oil may be supplied from the groove to parts to be lubricated, such as bearings and or toothing part. An advantage in this instance is that because oil is sprayed up onto the top wall, the oil is conveyed into the groove. In addition, with the aid of the pumping action of the gear wheel interacting with the trough, lubricating oil is able to be conveyed into the groove, so that sufficient oil is available for lubricating the parts to be lubricated, such as bearings or meshing gear-tooth parts.

A trough for guiding oil and reducing losses due to splashing may surround a circumferential section of a toothing part, particularly a gear wheel, especially in the radial and axial direction, the trough including at least three parts, e.g., at least one bottom plate and two side walls, the bottom plate being screw-connected to the two side walls, the trough being fastened to the housing, the trough having an opening, particularly a channel, especially at its lowest surface area, e.g., particularly at the surface area having the greatest radial distance, in particular, during rotational movement of the gear wheel, oil being conveyed from the oil pan of the gear unit through the opening between the trough and gear wheel, especially to a position higher than the level of the oil pan, the bottom plate and the side walls being stamped bent parts.

An advantage in this context is that with the aid of the gear wheel, oil is able to be delivered from the oil pan of the gear unit to a higher-situated location such as a temporary storage or a collecting channel, and thus from there, bearings and meshing gear teeth are able to be lubricated with lubricating oil. In addition, with the aid of the trough that, at least sectionally, correspondingly follows the contour of the gear wheel, therefore the outline of the rotating gear wheel, e.g., the cylindrical spatial area that is contacted by the rotating gear wheel, losses due to splashing are able to be reduced. To that end, the gap between the rotating gear wheel and the trough, especially the bottom plate of the trough, must be made small. The bottom plate is situated, with its surface section facing the gear wheel, at a radial distance that is set apart only slightly from the radial distance of the crowns of the gear teeth of the gear wheel to the axis of the gear wheel. Therefore, the surface section of the bottom plate facing the gear wheel extends substantially in the circumferential direction and in the axial direction, but with the exception of an opening, always has the same radial distance to the axis of the gear wheel, especially to the axis of the shaft to which the gear wheel is joined in rotatably fixed fashion.

The construction of the trough from only three parts forming it, namely, bottom plate and side walls, permits an especially cost-effective production by screw-connecting these parts.

In one advantageous embodiment, the distance, particularly the distance in the radial direction, between the bottom plate and the crowns of the gear teeth is constant in the angle-at-circumference area covered by the trough. This is considered advantageous because a small gap is sufficient as distance in order to achieve the pumping action. Losses due to splashing are therefore able to be reduced.

The bottom plate may have tab sections extending in the radial direction, at which the side walls are screw-connected. An advantage in this case is that the tab sections are able to be produced in an easy manner by bending a punching sheet. In addition, the tab section is able to be aligned parallel to the side wall, thus, perpendicular to the surface section of the bottom plate extending in the circumferential direction and in the axial direction. Therefore, a simple sturdy connection is attainable between the bottom plate and side wall. In the case of a production series of gear units in which gear wheels of different sizes are used, a transmission ratio that is different in each instance is achievable for each gear unit in the production series. Consequently, however, the bottom plate must be secured at a radial distance adjusted in each case, and thus the axially aligned screws of the screw connection between the bottom plate and side wall at different radial distance, accordingly.

A side wall may have a marking, at which a bore hole is able to be placed for leading through a screw of the screw connection. An advantage in this instance is that depending on the transmission ratio of the gear unit or size, especially the crown circle diameter, of the gear wheel, a bore hole is able to be placed at the radial distance indicated differently in each case, and thus the trough is able to be disposed at a different radial distance.

In one advantageous embodiment, the opening, especially the channel, is bounded by the bottom plate and the two side walls. This is considered advantageous because an oil-conveying opening is able to be produced in an inexpensive and uncomplicated manner.

The bottom plate and each side wall may in each instance be formed in one piece, e.g., integrally. This is considered advantageous because each of the three parts is able to be produced as a stamped bent part, e.g., in a very inexpensive and uncomplicated manner. In this context, even the two side walls are able to be similarly implemented.

The housing may be provided for a gear unit, the housing having a housing top part and a housing bottom part, the housing top part having a frame-like support section on which wall sections are molded, the frame-like support section being formed integrally, e.g., in one piece, with the wall sections, particularly as a casting, especially as a steel casting.

An advantage in this case is that only the support section must contain a lot of material, e.g., also mass, but not the wall sections. Therefore, great forces are able to be transmitted, while saving on material.

In one advantageous embodiment, the greatest wall thickness of the wall sections is less than the greatest wall thickness of the support section. An advantage in this instance is that the wall sections are able to be implemented with thin wall thickness, making it possible to realize the housing while saving on material.

The frame-like support section of the housing top part may have a first and a second transverse rib, in particular, the transverse ribs stretching mainly in the horizontal direction, e.g., in particular, being extended further in the horizontal direction than in any direction transverse to it, the frame-like support section having two first ribs, the two first ribs being set apart from each other and in each case being joined to the first transverse rib, especially at two points set apart from each other, in particular, the first ribs stretching mainly in the vertical direction, e.g., in particular, being extended further in the vertical direction than in any direction transverse to it, the two second ribs being set apart from each other and in each case being joined to the second transverse rib, especially at two points set apart from each other, in particular, the second ribs stretching mainly in the vertical direction, e.g., in particular, being extended further in the vertical direction than in any direction transverse to it. This is considered advantageous because especially high stability is attainable, accompanied by little expenditure for material. The reason is that the frame-like support section has a rectangular shape, in which the rectangle is bent out of the plane of the rectangle at its two opposite sides, so that the bent areas are located essentially in further planes that are perpendicular to the plane, are set apart from each other, and are parallel to each other.

Each first rib and each second rib may have a lifting eye at its end area facing away from the respective transverse rib. This is considered advantageous because the forces introduced into the housing during transport are introduced directly into the frame-like support section, and not into wall sections having thin wall thickness.

A first rib may be joined at its end area to a bar, especially a support bar, that is joined at its other end to the end area of a second rib, the other rib being joined at its end area to a bar, especially a support bar, that in turn is joined at its other end to the end area of the other second rib, in particular, the two bars being disposed in parallel and set apart from each other. This is considered advantageous because high stability is attainable with the aid of the bracings.

A shaft of the gear unit may be supported by a bearing in the housing, a first part of the bearing mounting being located in the housing top part and a second part of the bearing mounting being located in the housing bottom part, the first part of the bearing mounting being implemented as a thickened section, and being joined to that area of the transverse ribs at which the respective rib is also joined. An advantage in so doing is that an additional bracing of the frame-like support section is provided by the thickened areas.

A housing cover may close an opening in housing top part, the opening being surrounded by the frame-shaped support section, particularly with clearance, especially so that the frame-shaped support section does not directly contact the opening, but rather is set apart from the opening. An advantage in this case is that gear-unit parts are able to be inspected through the opening and maintenance work is able to be carried out. At the same time, no lubricating oil flows out from the gear unit either, since the opening is located on the upper side of the housing top part.

Among features with regard to the gear unit are that it is provided with a housing, a shaft of the gear unit being supported by a bearing in the housing, a first part of the bearing mounting being located in the housing top part and a second part of the bearing mounting being located in the housing bottom part, the first part of the bearing mounting being implemented as a thickened section, and being joined to that area of the transverse ribs at which the respective rib is also joined.

This is considered advantageous because high torsional stiffness and high mechanical stability are attainable.

Example embodiments of the present invention are explained in greater detail below with reference to the Figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an oblique view of a gear-unit housing according to an example embodiment of the present invention for a gear unit in a first viewing direction, the housing including a housing top part 1 and a housing bottom part 2.

FIG. 2 shows an oblique view of the gear-unit housing in another viewing direction.

FIG. 3 shows an oblique view of the gear-unit housing in a third viewing direction.

FIG. 4 shows an oblique view of housing bottom part 2.

FIG. 5 shows an oblique view of housing top part 1.

FIG. 6 shows the frame-like support section of housing top part 1.

As segment from housing top part 1, FIG. 7 shows a side wall section 3, which is inserted into the frame-like support section.

As a segment from housing bottom part 2, FIG. 8 shows a wall section having a wave structure, e.g., especially a concave-convex wall section.

FIG. 9 shows oil level 90.

FIG. 10 shows a gear wheel 100 of the gear unit that is mounted in rotatably fixed manner on a shaft 101 supported in the gear-unit housing, and is at least partially surrounded by a trough secured to housing bottom part 2.

FIG. 11 shows the trough itself in oblique view, the trough having side walls 102 and a bottom plate 103.

FIG. 12 shows a side wall 102 of the trough.

FIG. 13 shows bottom plate 103 of the trough.

FIG. 14 shows the trough without front side wall 102, so that the gear wheel is visible in oblique view, a first section being denoted.

FIG. 15 shows the first section from FIG. 14 enlarged, a second section being denoted.

FIG. 16 shows the second section from FIG. 15 enlarged.

FIG. 17 shows the housing of the gear unit cut into in the longitudinal direction, so that the curvature of the vault wall, especially the arched profile in the longitudinal direction, is visible.

FIG. 18 shows the housing of the gear unit cut into in the transverse direction, so that the curvature of the vault wall, especially the arched profile in the transverse direction, is visible.

DETAILED DESCRIPTION

As shown in FIG. 1 , a gear unit 10 includes a hosing 11 including a housing bottom part 2 disposed below housing top part 1. Thus, housing top part 1 is situated above housing bottom part 2 in the vertical direction. In FIG. 2 , housing is indicated by reference numeral 11.

Housing top part 1 has a frame-like support section 64, which takes up and conducts the major portion of the forces. The remaining sections of housing top part 1 are formed only for the oil-tight enclosure of the gear-unit interior, e.g., are formed with thinner wall thickness than the support section and join closely to the support section.

Consequently, housing top part 1 as well as housing bottom part 2 are formed in shell-like fashion.

The frame-like support section of housing top part 1 has a first transverse rib 62. It extends mainly in the horizontal direction.

Two first ribs 61 are set apart from each other, and in each case are joined to first transverse rib 61, particularly at two points set apart from each other.

First ribs 61 stretch mainly in the vertical direction, e.g., are extended further in the vertical direction than in any direction transverse to it.

The frame-like support section of housing top part 1 also has a second transverse rib 62. It extends mainly in the horizontal direction.

Two second ribs 61 are set apart from each other, and in each case are joined to second transverse rib 61, particularly at two points set apart from each other.

Second ribs 61 stretch mainly in the vertical direction, e.g., are extended further in the vertical direction than in any direction transverse to it.

Each first rib 61 and each second rib 61 has a lifting eye 63 at its end area facing away from the respective transverse rib. Thus, the gear unit is able to be picked up at the lifting eyes by hooks or cable and is easily transportable. The forces occurring during transport are introduced at lifting eyes 63 into the end areas and thus into the frame-like support section. Consequently, the gear-unit housing becomes only negligibly deformed and remains undamaged.

A first rib 61 is joined at its end area to a bar 60, particularly a support bar, which at its other end is joined to the end area of a second rib 61. In the same manner, the other rib 61 is joined at its end area to a bar 60, particularly a support bar, that in turn is joined at its other end to the end area of the other second rib 61. The two bars 60 are disposed in parallel and set apart from each other.

As described above, wall sections are conformed to the frame-like support section—formed thus of ribs 61, transverse ribs 62 and bars 60—of housing top part 1, so that the shell-like housing top part is able to be formed in one piece, particularly as a casting.

In this connection, the wall sections, especially also two side wall sections 3 and the wall section having a concave-convex wave structure, are thus integrally molded and conformed to the frame-like support section and implemented in one piece.

Bars 60 stretch mainly in the horizontal direction, e.g., are extended further horizontally than in any direction transverse to that.

The frame-like support section is thus realized by an increase in the wall thickness.

In addition, thickened areas 8 are also provided on housing top part 1, which are intended as bearing mounting for at least one part, especially half, of the circumference of an outer ring of a bearing. These arch-like thickened areas adjoining one another are joined to transverse ribs 62, especially in each case in that end area in which respective rib 61 is joined.

The concave-convex wave structure of the wall sections enlarges the surface area, and therefore reduces resistance to the transfer of heat to the ambient air. In this context, an especially sharp depression is provided as depression 5 for a manipulation area for screw connections. In this case, the screws are connecting screws by which housing top part 1 and housing bottom part 2 are screw-connected.

Housing bottom part 2 has a wave structure 6, particularly a concave-convex wall section, which likewise enlarges the surface area, and therefore reduces resistance to the transfer of heat from the gear-unit interior, especially lubricating oil, to the ambient air.

The housing cover is provided to close an opening 7 in housing top part 1, the opening being surrounded by the frame-shaped support section, especially with clearance. That means that the frame-shaped support section does not directly contact the opening, but rather is set apart from the opening.

As shown in FIG. 10 , gear wheel 100 is joined in rotatably fixed manner to shaft 101, which is supported in the housing by a bearing 107. In this context, the bearing is accommodated in a bearing mounting in the housing, a first part 9 of the bearing mounting being located in housing top part 1 and a second part 12 of the bearing mounting being located in housing bottom part 2.

The lower spatial area surrounding gear wheel 100 is enclosed by the trough, the trough having side walls 102 and a bottom plate 103. Thus, it is able to be fabricated from three parts.

Side walls 102 of the trough are secured to bottom plate 103. At its lowest area, bottom plate 103 has a protuberance 130 directed downward. Protuberance 130 is directed radially away from the gear wheel, and is open at its radially outer end area. Thus, lubricating oil of the gear unit gets from the oil pan of the gear unit through protuberance 130 up to gear wheel 100. Laterally, e.g., on both sides in the axial direction, the protuberance is closed by a respective tab section 120 of side walls 102, so that a channel is formed passing through radially to gear wheel 100.

As illustrated FIG. 12 , in each case side walls 102 are punched out as a sheet-metal part, and at their axial outer side, have markings which identify the positions of bore holes to be introduced, particularly as a function of the transmission ratio of the gear unit and/or toothing data of gear wheel 100.

Screws 104 are guided through the bore holes, making a screw connection achievable between bottom plate 103 and respective side wall 102.

Therefore, depending on the size or other toothing data, the bottom plate is able to be positioned at an optimal radial distance from the central axis of the gear wheel.

Bottom plate 103 is likewise produced as a stamped bent part, and has a U-shaped cross-section. In this context, it is bent such that the distance between the toothing, particularly the crowns of the teeth of the toothing of gear wheel 100 located in the same angle at circumference as bottom plate 103, is constant. Thus, a narrow gap is provided between these tooth crowns and bottom plate 103.

Consequently, a pumping action develops during rotational movement of gear wheel 100, since the lubricating oil located in the tooth spaces is moved with greater velocity than the lubricating oil in the channel. In this manner, lubricating oil 106 is thus conveyed through the channel or opening 132 from the oil pan 105 to gear wheel 100 and is then moved along with it.

The trough also reduces the losses due to splashing during movement of gear wheel 100, for the teeth of the toothing of gear wheel 100 dip in the spatial area surrounded by the trough.

With the exception of tab sections 120 and protuberance 130, U-shaped bottom plate 103 is bent circularly in the circumferential direction, so that the distance between the teeth of the toothing of gear wheel 100 and bottom plate 103 is essentially constant in the corresponding angle-at-circumference area.

Tab sections 120 are directed radially to the outside, so that respective side wall 102 is able to be pressed in the axial direction onto bottom plate 103, particularly at its tab sections 120, and screw-connected.

With the aid of the pumping action of gear wheel 100 in interaction with the trough, oil is pumped to a position situated higher than the oil level of the oil pan, and from there is conducted via a temporary storage or directly to the places to be lubricated, such as bearings or engaging gear teeth. Appropriate conduits or pipes are provided for this purpose.

Protuberance 130 is able to be produced by bending out from the original form of bottom plate 103. To that end, a punching sheet is bent such that two areas, bent in the shape of circle segments, are set apart from each other over an area bent substantially in the shape of a rectangle. After that, the areas bent in the shape of circle segments are pressed against each other, and thus form the circular area of bottom plate 103. At the same time, the areas bent in the shape of circle segments encompass an opening. The area bent in the shape of a rectangle likewise has a centrally located opening and thus forms protuberance 130.

As illustrated in FIGS. 17 and 18 , top wall 171 is curved, a differently curved profile being present in the longitudinal direction L than in the transverse direction T, the longitudinal direction L and transverse direction T defining a plane. In this case, the inclination is such that oil droplets which, for example, are sprayed by a gear wheel 100 of the gear unit up onto the ceiling, preferably flow off in the transverse direction T along top wall 171. Below top wall 171, particularly below the end area of top wall 171 situated in the longitudinal direction L, a longitudinal groove is formed whose groove wall 170 extends in the longitudinal direction L, e.g., extends further in the longitudinal direction L than in the transverse direction T or other direction perpendicular to the longitudinal direction L. In the same manner, a transverse groove 173 is located below the end area of top wall 171 disposed counter to the longitudinal direction L.

Thus, the oil sprayed up onto top wall 171 flows off either in the longitudinal direction or counter to the longitudinal direction to the respective end area of top wall 171, and drips down into the respective groove. From there, the oil is guided to a bearing to be lubricated or to a toothing part to be lubricated.

The groove is formed in one piece on housing top part 1, e.g., by shaping of the steel casting, and therefore is formed integrally with housing top part 1.

From the highest point 174 of concave top wall 171, the oil flows off faster in the transverse direction than in the longitudinal direction, because the curvature and gradient are greater in the transverse direction. As mentioned above, the amount of the gradient of the top wall 171, e.g., especially the slope of the top wall 171 relative to the horizontal direction, increases faster in the transverse direction T with increasing distance from the highest point 174 of the top wall 171, especially from the surface point of the top wall with vanishing gradient 175, than in the longitudinal direction L.

The top wall is extended further in the longitudinal direction than in the transverse direction.

Oil-flow direction 172 on top wall 171 is therefore directed outward, e.g., directed in the longitudinal direction or counter to the longitudinal direction, and consequently the oil droplets are conveyed toward the groove.

Therefore, not only is oil conveyed to a higher position, especially into the groove, by the conveying effect of the gear wheel together with the trough, but also the oil spraying around is conveyed into the groove. Consequently, sufficient oil is available for lubrication.

LIST OF REFERENCE CHARACTERS

-   1 housing top part -   2 housing bottom part -   3 side wall section -   4 housing cover -   5 depression for manipulation area for screw connections -   6 wave structure, especially concave-convex wall section -   7 opening -   8 thickened area -   9 first part -   10 gear unit -   11 housing -   12 second part -   60 bar -   61 rib -   62 transverse rib -   63 lifting eyes -   64 support section -   90 oil level -   100 gear wheel -   101 shaft -   102 side wall -   103 bottom plate -   104 screw -   105 oil pan -   106 oil -   107 bearing -   120 tab section -   130 protuberance -   132 channel or opening -   170 groove wall -   171 top wall -   172 oil-flow direction on top wall 171 -   173 transverse groove -   174 highest point of the top wall 171 -   175 surface point of the top wall 171 with vanishing gradient -   L longitudinal direction -   T transverse direction 

What is claimed is:
 1. A gear unit, comprising: a housing including a housing top part and a housing bottom part, the housing top part having a top wall that at least partially delimits an interior of the gear unit and is curved and/or concave, an inner side of the housing top part including a groove adapted to receive oil droplets sprayed up toward the top wall that drip off in or counter to a transverse direction along the top wall into the groove; wherein a slope of the top wall relative to a plane defined by the transverse direction and a longitudinal direction perpendicular to the transverse direction, increases greater in the transverse direction with increasing distance from a highest point of the top wall than in the longitudinal direction.
 2. The gear unit according to claim 1, wherein the groove includes a longitudinal groove extending in the longitudinal direction and a transverse groove extending in the transverse direction.
 3. The gear unit according to claim 2, wherein the longitudinal groove extends along an entire longitudinal length of the inner side of the housing top part.
 4. The gear unit according to claim 3, wherein the transverse groove extends along an entire transverse length of the inner side of the housing top part.
 5. The gear unit according to claim 2, wherein the transverse groove extends along an entire transverse length of the inner side of the housing top part.
 6. The gear unit according to claim 1, wherein the transverse direction is aligned parallel to an axis of a shaft of the gear unit.
 7. The gear unit according to claim 1, wherein the top wall is vaulted.
 8. The gear unit according to claim 1, wherein the groove is adapted to supply lubricating oil from the groove to parts, bearings, and/or toothing parts.
 9. The gear unit according to claim 1, wherein a trough adapted to guide oil and reduce losses due to splashing surrounds a circumferential section of a toothing part and/or a gear wheel in radial and/or axial directions, the trough including at least three parts, including at least one bottom plate and two side walls, the bottom plate being screw-connected to the two side walls, the trough being fastened to the housing, the trough having an opening and/or a channel at a lowest surface area and/or at a surface area having a greatest radial distance, during rotational movement of the toothing part and/or the gear wheel, oil being conveyed from an oil pan of the gear unit through the opening between the trough and the toothing part and/or the gear wheel, to a position higher than a level of the oil pan, into the groove, the bottom plate and the side walls being stamped bent parts.
 10. The gear unit according to claim 9, wherein (a) a distance and/or a distance in the radial direction, between the bottom plate and crowns of the gear teeth is constant in an angle-at-circumference area covered by the trough, (b) the bottom plate has tab sections extending in the radial direction, at which the side walls are screw-connected, (c) one side wall has a marking at which a bore hole is pleaceable adapted to lead through a screw of a screw connection, and/or (d) the opening and/or the channel is bounded by the bottom plate and the two side walls.
 11. The gear unit according to claim 9, wherein the bottom plate and each side wall are formed in one piece and/or integrally.
 12. The gear unit according to claim 1, wherein the housing top part has a frame-shaped support section on which wall sections are molded, the support section being formed integrally and/or in one piece with the wall sections as a casting and/or as a steel casting.
 13. The gear unit according to claim 12, wherein a greatest wall thickness of the wall sections is less than a greatest wall thickness of the support section.
 14. The gear unit according to claim 12, wherein the support section of the housing top part includes a first transverse rib and a second transverse rib, the transverse ribs extending further in a direction parallel to the plane defined by the transverse and longitudinal directions than in any direction transverse to the direction parallel to the plane defined by the transverse and longitudinal directions, the support section having two first ribs, the two first ribs being set apart from each other and in each case being joined to the first transverse rib, at two points set apart from each other, the first ribs extending further in a direction perpendicular to the plane defined by the transverse and longitudinal directions than in any direction transverse to the direction perpendicular to the plane defined by the transverse and longitudinal directions, two second ribs being set apart from each other and in each case being joined to the second transverse rib, at two points set apart from each other, the second ribs extending further in the direction perpendicular to the plane defined by the transverse and longitudinal directions than in any direction transverse to the direction perpendicular to the plane defined by the transverse and longitudinal directions.
 15. The gear unit according to claim 14, wherein each first rib and each second rib includes a lifting eye at an end area facing away from a respective transverse rib.
 16. The gear unit according to claim 14, wherein a first rib is joined at an end area to a bar and/or to a support bar that is joined at its other end to an end area of a second rib, another first rib being joined at an end area to a bar and/or to a support bar that is joined at its other end to an end area of the other second rib, the two bars and/or the two support bars being arranged in parallel and set apart from each other.
 17. The gear unit according to claim 12, wherein a housing cover closes an opening in the housing top part, the opening being surrounded by the support section, such that the support section does not directly contact the opening and is set apart from the opening.
 18. The gear unit according to claim 14, wherein a shaft of the gear unit is supported by a bearing in the housing, a first part of a bearing mounting being located in the housing top part and a second part of the bearing mounting being located in the housing bottom part, the first part of the bearing mounting including a thickened section, and being joined to an area of a transverse ribs at which one of the support ribs is also joined.
 19. The gear unit according to claim 1, wherein the groove extends around an entire perimeter of the inner side of the housing top part. 